Guillermo E. Defossé, Ronald Robberecht, and Mónica
B. Bertiller. 1996. Seedling dynamics of Festuca
in Patagonia: Competition, microsites, and grazing. Journal
of Range Management 50:73-79.
Abstract The effects of competition, grazing, and microsites
on seedling dynamics of Festuca spp. were investigated
in a semiarid steppe of Patagonia, Argentina. In an exclosure
and an adjacent grazed area, the level of root competition for
seedlings was controlled through root exclusion tubes (0.1 m diameter,
0.4 m long) installed adjacent to seven similarly-sized Festuca
pallescens plants and in the interspace between F. pallescens
plants. Seedling dynamics at the phenological stages
of a) recently emerged and up to four leaves and b) five leaves
and up to one tiller were followed inside the tube area (no competition)
and in paired circles (competition) for approximately three growing
seasons. Peak density of Festuca spp. seedlings occurred
in fall and early spring, when water content in the first 0 to
5 cm of the soil was above 8%. Seedling densities of Festuca
spp. at the two phenological stages were significantly
reduced by grazing. At the phenological stage of one to four
leaves, seedlings were not affected by root competition, although
their densities were significantly higher for seedlings adjacent
to F. pallescens plants than in the interspace between
plants. This was due to higher soil water content in these areas
throughout the season in the 0 to 5 cm of the soil. Seedling
densities at the phenological stage of five leaves and up to one
tiller were significantly higher when there was no competition
from neighboring grass plants as compared to seedlings exposed
to competition. In regard to microsite differences, seedling
density was significantly greater in the interspaces than adjacent
to mature plants. These results suggest that although higher
seedling densities can be obtained by excluding the area from
grazing, intraspecific competition for soil water during the summer
drought period can act as a barrier for further Festuca spp.
seedling establishment.
This study was funded by a grant
from the Consejo Nacional de Investigaciones Científicas
y Técnicas (CONICET) de la República Argentina (PID
3058100/88). Contribution no. 799 of the Forest, Wildlife, and
Range Experiment Station, University of Idaho.